Gasoline formulations have in recent years often included significant quantities of tetramethyllead as an antiknock agent. Tetramethyllead, unlike tetraethyllead, is produced from methyl halide and sodium-lead alloy only with considerable difficulty and normally requires the presence of a catalyst in the reaction zone. Thus, U.S. patents such as U.S. Pat. Nos. 3,048,610; 3,192,420 and 3,401,188 and British Patent No. 1,015,268 all describe various processes for the manufacture of tetramethyllead from sodium-lead alloy and methyl halide utilizing various catalyst systems.
While the catalyst systems described in the prior art are efficacious in the production of tetramethyllead in satisfactory quantities, drawbacks are encountered in the utilization of most of them. Thus, various aluminum containing catalysts described in the prior art are found to be somewhat difficult to handle in that they are subject to spontaneous ignition. The utilization of other catalysts such as ammonia in the presence of small quantities of monohydroxylic compounds, as described in the aforementioned British patent, requires sophisticated equipment in order to avoid leaks during reaction. Therefore, while tetramethyllead is capable of being produced in accordance with the various catalyst systems described in the prior art, some of the disadvantages inherent in these prior art catalyst systems are not easily overcome.